Atomic rearrangement from disordered to ordered Pd-Fe nanocatalysts with trace amount of Pt decoration for efficient electrocatalysis. (August 2018) - Xiao, Weiping
Abstract: The structure-activity relationship between the ORR performance and the surface electronic structure of Pd is constructed and the ORR performance are rationally modified via the structural transition from disordered face centered cubic phase (fcc, D-PdFe/C) to ordered intermetallic tetragonal phase (fct, O-PdFe/C). When the small amount of Pt atoms decorated on O-PdFe/C surface forming O-PdFe@Pt/C core-shell structure, the sublayer of Pd and Fe atoms may cause the lattice contraction of surface Pt and then weak the bonding energy on O-PdFe@Pt/C catalyst relative to bulk Pt/C, which is further illustrated by density functional theory (DFT) calculation. The weakened oxygen affinity results in the enhancement of ORR performance on O-PdFe@Pt/C. For a practical application, the well-constructed O-PdFe@Pt/C exhibits higher voltage and peak power density than D-PdFe@Pt/C and Pt/C when applied as the air-breathing cathode material in Zn-air battery. Graphical abstract: The excellent ORR electrocatalytic performance on O-PdFe@Pt/C is originated from the interaction between high active O-PdFe/C core and ultralow content of Pt shell. This work provides new insights for the future optimization high efficiency ORR catalysts. fx1 Highlights: The structurally ordered PdFe/C intermetallics were prepared by an impregnation reduction method. The ultralow content of Pt was decorated on ordered PdFe/C with excellent activity and stability for ORR. DFT calculations indicated a weakened oxygen affinity on Pt shell caused by ordered PdFe core.